Ampicillin

Semi-synthetic, antibiotically active drug from the group of betalactam antibiotics (aminopenicillins). Because of its effectiveness against Gram-positive pathogens (as well as some Gram-negative rods), ampicillin is called a broad-spectrum antibiotic or broad-spectrum penicillin.

The bacteriolytic effect of ampicillin starts with the division of bacteria and, as with all betalactam antibiotics, is based on the blocking of the enzyme D-alanine transpeptidase, which is necessary for the formation of a new cell wall. Ampicillin thus prevents the new synthesis of a stable bacterial cell wall.

• 1.5-4 g/day i.v. in 3-4 ED.
• Children from 3 months: 250-670 mg/day.
• Children from 6 months: 300-800 mg/day.
• Children from 1 year: 375-1000 mg/day.
• Children from 3 years: 500-1300 mg/day.
• Children from 7,5 years: 750-2000 mg/day.
• Children from 12 years: 1-2,7 g/day.

Remember! For sepsis and meningitis, double the dose!

In the case of oral contraceptives, influencing the intestinal flora can lead to reduced uptake of the contraceptives into the blood and thus to reduced efficacy.

Indomethacin, phenylbutazone, probenecid, salicylates and sulfinpyrazone lead to prolonged and increased blood concentrations of penicillins and should therefore not be taken together with penicillins.

Ampicillin reduces the renal excretion of methotrexate.

Remember! The poorer enteral absorption of ampicillin compared to other broad-spectrum penicillins such as amoxicillin should be considered when using it for oral therapy. Relatively high exanthema and allergy rate in the whole group (also in combination with ß-lactamase inhibitor), see also under penicillin allergy.

For the special features of the so-called ampicillin exanthema in infectious mononucleosis, see Epstein-Barr virus below.

1. Arnez M (2007) Antibiotic treatment of children with erythema migrans. Clin Infect Dis 44: 1133-1134